/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.library.drepair.util;

import org.apache.commons.lang3.tuple.Pair;
import org.apache.commons.math3.stat.descriptive.rank.Median;
import org.apache.iotdb.library.util.Util;
import org.apache.iotdb.udf.api.access.RowIterator;

import java.util.ArrayList;
import java.util.Arrays;

public class Screen extends ValueRepair {

    private double smin, smax;
    private double w;

    public Screen(RowIterator dataIterator) throws Exception {
        super(dataIterator);
        setParameters();
    }

    private void setParameters() {
        // set the default speed threshold
        double[] speed = Util.speed(original, time);
        Median median = new Median();
        double mid = median.evaluate(speed);
        double sigma = Util.mad(speed);
        smax = mid + 3 * sigma;
        smin = mid - 3 * sigma;
        // set the default window size
        double[] interval = Util.variation(time);
        w = 5 * median.evaluate(interval);
    }

    @Override
    public void repair() {
        // fixed window
        ArrayList<Pair<Long, Double>> ans = new ArrayList<>();
        ans.add(Pair.of(time[0], original[0]));
        int startIndex = 0;
        for (int i = 1; i < n; i++) {
            ans.add(Pair.of(time[i], original[i]));
            while (ans.get(startIndex).getLeft() + w < ans.get(i).getLeft()) {
                // sliding window
                local(ans, startIndex);
                startIndex++;
            }
        }
        while (startIndex < n) {
            local(ans, startIndex);
            startIndex++;
        }
        int k = 0;
        for (Pair<Long, Double> p : ans) {
            this.repaired[k] = p.getRight();
            k++;
        }
    }

    private double getMedian(ArrayList<Pair<Long, Double>> list, int index) {
        int m = 0;
        while (index + m + 1 < list.size()
                && list.get(index + m + 1).getLeft() <= list.get(index).getLeft() + w) {
            m++;
        }
        double[] x = new double[2 * m + 1];
        x[0] = list.get(index).getRight();
        for (int i = 1; i <= m; i++) {
            x[i] =
                    list.get(index + i).getRight()
                            + smin * (list.get(index).getLeft() - list.get(index + i).getLeft());
            x[i + m] =
                    list.get(index + i).getRight()
                            + smax * (list.get(index).getLeft() - list.get(index + i).getLeft());
        }
        Arrays.sort(x);
        return x[m];
    }

    private double getRepairedValue(ArrayList<Pair<Long, Double>> list, int index, double mid) {
        double xmin =
                list.get(index - 1).getRight()
                        + smin * (list.get(index).getLeft() - list.get(index - 1).getLeft());
        double xmax =
                list.get(index - 1).getRight()
                        + smax * (list.get(index).getLeft() - list.get(index - 1).getLeft());
        double temp = mid;
        temp = Math.min(xmax, temp);
        temp = Math.max(xmin, temp);
        return temp;
    }

    private void local(ArrayList<Pair<Long, Double>> list, int index) {
        double mid = getMedian(list, index);
        // 计算x_k'
        if (index == 0) {
            list.set(index, Pair.of(list.get(index).getLeft(), mid));
        } else {
            double temp = getRepairedValue(list, index, mid);
            list.set(index, Pair.of(list.get(index).getLeft(), temp));
        }
    }

    public void setSmin(double smin) {
        this.smin = smin;
    }

    public void setSmax(double smax) {
        this.smax = smax;
    }

    public void setW(int w) {
        this.w = w;
    }
}
